RFR: 8236651: Simplify and update glass gtk backend

[Thiago Milczarek Sayao]

On Thu, 13 Feb 2020 23:56:42 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> **Code Changes**
>> 
>> * glass_window.cpp / glass_window.h
>>     * Removed WindowContextPlug and WindowContextChild (that were used for applets / web start) and moved everything to
>> one class named WindowContext (since inheritance was no required anymore)
>>     * Changed set_enabled() to use gtk_widget_set_sensitive instead of custom code;
>>     * Moved to gtk signals instead of gdk events (to use gtk_widget_set_sensitive and gtk_grab_add);
>>     * Frame Extents: Removed the code to request extents and gtk already does it by default;
>>     * Size calculation: Reworked size calculation code. In general, X windows are content size instead of whole window size (considering extents - frame decorations). OpenJfx uses "whole window size" as  window sizes, so it requires a "hack" to recalculate sizes when set_bounds() is called with window sizes instead of content sizes. The rework was to simplify code paths and make it more straightforward.
>>     * Other Size calculation changes:
>>         * Use gtk_window_set_default_size() for initial size which is the appropriate function; 
>>         * Gravity is now ignored as it is on Windows glass impl;
>>         * Avoid sending same sizes to Java;
>>         * Introduced calculate_adjustments() which is a fallback when frame extents is not present (it's optional  to window managers to implement it);
>>     * Geometry: Min / Max sizes - reworked it to simplify / Concentrated geometry changes on
>>       apply_geometry().
>>     * Mouse grab: Reworked it to use to correct functions according to gtk+ version;
>>     * Draw: Reworked it to use the correct calls accord to gtk+ version changes;
>>     * Fixed JDK-8237491;
>>     * Moved background code to paint() as gtk3 uses styles to set the background and other functions were deprecated;
>>     * Reorganized function order on glass_window.cpp to match glass_window.h
>> 
>> 
>> * GlassCursor.cpp
>>     * Gtk+3 uses a name-like-css approach - so it was properly ported to gtk3 way;
>>     * Reworked Gtk+2 to use a function instead of manual calls to find the cursor;
>> 
>> * GtkWindow.java
>>     * Moved the extents special case to native glass;
>> 
>> * GlassApplication.cpp
>>     * Removed Gdk events where possible (it's now on glass_window as signals);
>>     * Removed applet/web start code;
>> 
>> * GlassView.cpp
>>     * Changes to reflect frame extents rework on glass_window
>> 
>> * GlassWindow.cpp
>>     * WindowContextTop -> WindowContext
>>     * Removed applet / web start code;
>>     * Removed frame extents (which is not called anymore due to GtkWindow.java change);
>> 
>> * glass_general.cpp
>>     * Removed functions that became unused;
>>     * Added is_grab_disabled() that is used on glass_window
>> 
>> * glass_window_ime.cpp
>>     * WindowContextTop -> WindowContext;
>>     
>> * glass_dnd.cpp / glass_dnd.h
>>     * Ported to Gtk signals;
>>     * Use all possible image formats (supported by GdkPixbuf / OpenJfx) - .gif is now possible (for ex.);
>>     * Allow COMPOUND_TEXT;
>>     * Do not request content while dragging;
>>     * Reduce overall code size.
>
> This is going to need further discussion on the mailing list as indicated above, so it is still premature to review it (i.e., it should still be considered effectively a "WIP" until that discussion happens). Additionally, this is a significant and risky change, so I'd like additional eyes on it when we do get to the point of reviewing it.

I have been testing this for several days on ubuntu 18.04 and it's working good. It pass system tests, runs Ensemble 8 and Scenebuilder.

Will have to do some tests on 16.04.

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PR: https://git.openjdk.java.net/jfx/pull/77